Jay Z shows in New York are always a big deal, and anytime a band as big as No Doubt plays its first show in two years, that’s a big deal, too. This fall, both will headline the Global Citizen Festival, a gigantic free show at the Great Lawn in New York’s Central Park. The festival aims to increase awareness of global poverty, and to earn tickets to the show, which goes down 9/27, you have to take part in a few awareness-raising activities, like watching videos and signing petitions; you can find out how to do all that stuff here. That tiny bit of work gets you in to witness the head-spinningly strange but weirdly impressive lineup of Jay Z, No Doubt, Carrie Underwood, Fun., the Roots, and Tiësto. All the relevant info is here.